Fluorosulfonyl group-containing monomer and its polymer, and sulfonic acid group-containing polymer

ABSTRACT

To provide a fluorosulfonyl group-containing monomer having a high polymerization reactivity and plural fluorosulfonyl groups. Further, to provide a fluorosulfonyl group-containing polymer and a sulfonic acid group-containing polymer, obtained by using the monomer. 
     A perfluoro(2-methylene-1,3-dioxolane) derivative which is represented by the following formula (3) and which has two fluorosulfonyl groups, and its production process and its synthetic intermediate. A fluorosulfonyl group-containing polymer having monomer units represented by the following formula (3U) obtained by polymerizing the compound (3) by itself or with a comonomer, and a sulfonic acid group-containing polymer having the following units (5U) obtained by hydrolyzing a fluorosulfonyl group of the polymer. In the following formulae, each of R f1  and R f2  which are independent of each other, is a C 1-8  perfluoroalkylene group which may have an etheric oxygen atom between carbon atoms.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fluorosulfonyl group-containingpolymer which is a precursor of a sulfonic acid group-containing polymeruseful as an ion-exchange membrane (e.g. a membrane to be used for brineelectrolysis or polymer electrolyte fuel cells) or an electrolytemembrane to be used for a catalyst layer of a fuel cell; and a newfluorosulfonyl group-containing monomer which can be a raw material ofthe polymer. Further, the present invention relates to a process forproducing the fluorosulfonyl group-containing monomer and a new compounduseful as an intermediate for production of the monomer. Furthermore, itrelates to a sulfonic acid group-containing polymer obtainable from theabove fluorosulfonyl group-containing polymer and an electrolytematerial for polymer electrolyte fuel cells, which comprises thesulfonic acid group-containing polymer.

2. Discussion of Background

Heretofore, a copolymer of a fluorinated monomer of the followingformula and tetrafluoroethylene, has been used as a membrane for brineelectrolysis, a membrane of a polymer electrolyte fuel cell or itscatalyst layer. In the following formula, Y is a fluorine atom or atrifluoromethyl group, n is an integer of from 1 to 12, m is an integerof from 0 to 3, k is 0 or 1, and m+k>0;

CF₂—CF—(OCF₂CFY)_(m)—O_(k)—(CF₂)_(n)—SO₂F

Further, the fluorosulfonyl group (—SO₂F) in the copolymer can beconverted to a sulfonic acid group (—SO₃H) by alkali hydrolysis,followed by acid treatment.

When used for a brine electrolysis cell as a membrane having a highion-exchange capacity, such a sulfonic acid group-containing polymer(hereinafter referred to as the sulfonic acid polymer) is a polymerwhich can reduce the power for the electrolysis. When the sulfonic acidpolymer is used for a fuel cell, the polymer can improve the powergeneration energy efficiency. Further, the sulfonic acid polymer ispreferably a polymer having a higher ion-exchange capacity and a lowerelectric resistance.

However, if the proportion of the fluorosulfonyl group-containingmonomer to be used for copolymerization, is increased for a purpose ofincreasing the ion-exchange capacity of the sulfonic acid polymer, therehas been a problem such that the molecular weight of the copolymerbecomes low. A membrane formed by the copolymer having low molecularweight is insufficient in mechanical strength and durability, and thusit is not practically useful. It has been proposed to use afluorosulfonyl group-containing monomer having plural fluorosulfonylgroups as a means to increase the ion-exchange capacity of the sulfonicacid polymer without increasing the proportion of the fluorosulfonylgroup-containing monomer (Patent Document 1).

Further, in order to obtain a sulfonic acid polymer having a highmolecular weight, the fluorosulfonyl group-containing monomer isrequired to have high copolymerizability with other fluoromonomers suchas tetrafluoroethylene, but the conventional fluorosulfonyl asgroup-containing monomer did not sufficiently have suchcopolymerizability. As a fluorosulfonyl group-containing monomer havinga high polymerization reactivity, a perfluoro(2-methylene-1,3-dioxolane)derivative having a fluorosulfonyl group is known (Patent Documents 2, 3and 4). However, such a derivative having plural fluorosulfonyl groupsis not known.

Patent Document 1: WO2007/013532

Patent Document 2; WO03/037885

Patent Document 3: JP-A-2005-314388

Patent Document 4: JP-A-2006-290864

SUMMARY OF THE INVENTION

The present invention has an object to provide an electrolyte materialfor polymer electrolyte fuel cells, which is an electrolyte materialhaving a high ion-exchange capacity and low resistance, and which has ahigher softening point than a commonly used electrolyte material and isexcellent in durability. Further, the present invention has an object toprovide a new monomer and a polymer to prepare such a material.

The present invention provides a fluorosulfonyl group-containing monomerhaving a high polymerization reactivity and plural fluorosulfonylgroups. The perfluoro(2-methylene-1,3-dioxolane) derivative having twofluorosulfonyl groups of the present invention is a new monomer.

The present invention is the following invention, which relates to afluorosulfonyl group-containing perfluoromonomer having twofluorosulfonyl groups and a high polymerization reactivity; itsproduction process and its synthetic intermediate; a fluorosulfonylgroup-containing polymer obtained by polymerizing the perfluoromonomer;a process for producing a sulfonic acid polymer from the polymer; andthe sulfonic acid polymer and an electrolyte material for polymerelectrolyte fuel cells, which comprises the sulfonic acid polymer.

(1) A compound represented by the following formula (3):

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.(2) The compound according to the above (1), wherein each of—R^(f1)—SO₂F and R^(f2)—SO₂F is a perfluorinated 2-fluorosulfonyl ethoxygroup-substituted alkylene group (the alkylene group has 1 to 3 carbonatoms).(3) A process for producing a compound represented by the followingformula (3) which comprises heat-decomposing a compound represented bythe following formula (2);

wherein each of R^(f3) and R^(f2) which are independent of each other,is a C₂₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.(4) The process according to the above (3), wherein each of —R^(f1)—SO₂Fand —R^(f2)—SO₂F is a perfluorinated 2-fluorosulfonyl ethoxygroup-substituted alkylene group (the alkylene group has 1 to 3 carbonatoms).(5) The process according to the above (3) or (4), wherein the compoundrepresented by the above formula (2) is produced from a compoundrepresented by the following formula (1) through (a) a step ofepoxidation, (b) a step of forming a dioxolane ring and (c) a step offluorination:

wherein each of R¹ and R² which are independent of each other, is a C₁₋₈alkylene group which may have an etheric oxygen atom between carbonatoms and of which some or all of hydrogen atoms may be substituted byfluorine atoms.(6) The process according to the above (5), wherein each of —R²—SO₂F and—R²—SO₂F is a 2-fluorosulfonyl-tetrafluoroethoxy group-substitutedalkylene group (the alkylene group has 1 to 3 carbon atoms).(7) A compound represented by the following formula (2):

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.(8) The compound according to the above (7), wherein each of—R^(f1)—SO₂F and —R^(f2)—SO₂F is a perfluorinated 2-fluorosulfonylethoxy group-substituted alkylene group (the alkylene group has 1 to 3carbon atoms).(9) A process for producing a fluorosulfonyl group-containing polymer,which comprises polymerizing at least one compound represented by thefollowing formula (3), or at least one such a compound and at least onepolymerizable monomer copolymerizable with such a compound:

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.(10) A fluorosulfonyl group-containing polymer comprising at least onetype of monomer units represented by the following formula (3U), or atleast one type of such monomer units and at least one type of othermonomer units;

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.(11) The fluorosulfonyl group-containing polymer according to the above(10), which has a molecular weight of from 5×10³ to 5×10⁶, and which,when containing said other monomer units, contains from 0.1 to 99.9 mol% of monomer units represented by the formula (3U).(12) A process for producing a polymer containing sulfonate groups orsulfonic acid groups, which comprises subjecting the fluorosulfonylgroup in the fluorosulfonyl group-containing polymer according to theabove (10) or(11) to an alkali hydrolysis, or to such an alkali hydrolysis, followedby an acid treatment.(13) A sulfonic acid group-containing polymer containing at least onetype of units represented by the following formula (5U), or at least onetype of such units and at least one type of other units:

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.(14) The sulfonic acid group-containing polymer according to the above(13), which has a molecular weight of from 5×10³ to 5×10⁶, and which,when containing other units, contains from 0.1 to 99.9 mol % of unitsrepresented by the formula (5U).(15) An electrolyte material for polymer electrolyte fuel cells, whichcomprises the sulfonic acid group-containing polymer according to theabove (13) or (14).

The monomer of the present invention is a perfluoromonomer having aperfluoro(2-methylene-1,3-dioxolane) structure having a highpolymerization reactivity and two fluorosulfonyl groups, whereby it iseasy to obtain a copolymer having a high molecular weight bycopolymerizing it with a copolymerizable monomer such astetrafluoroethylene, and it is easy to obtain a sulfonic acid polymerhaving high mechanical strength and durability. Further, since themonomer of the present is invention has two fluorosulfonyl groups, it ispossible to obtain a sulfonic acid polymer having a high ion-exchangecapacity even if its copolymerization ratio is low, as compared with amonomer having one fluorosulfonyl group.

The sulfonic acid polymer of the present invention is useful as anelectrolyte material for polymer electrolyte fuel cells since it has alow electric resistance owing to its high ion-exchange capacity; has ahigh softening point and excellent mechanical strength; and further hasdurability. Since the electrolyte material has a high softening point,it is possible to operate a cell at a higher temperature thanconventional ones, and it is possible to make the fuel cell have a highoutput or improve the cooling efficiency.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present specification, a compound represented by the formula (3)is shown as a compound (3). Further, a group represented by the formula(3a) is shown as a group (3a), and units represented by the formula (3U)are shown as units (3U). A polymer containing units (3U) is shown as apolymer (3U). The same applies to compounds, groups, units or polymersrepresented by other formulae.

Units in a polymer mean units derived from a monomer as formed bypolymerization of the monomer, and the units in the present inventionmay be units directly formed is from a polymerization reaction or unitsformed by a chemical conversion after the polymerization reaction. Amongsuch units, the units maintaining the monomer structure except for theunsaturated groups which transform by polymerization reaction of themonomer, are referred to as monomer units.

Hereinafter, a fluorosulfonyl group may also be shown as a —SO₂F group,a fluorocarbonyl group as a —COF group and a sulfonic acid group as a—SO₃H group.

The present invention provides the following compound (3).

In the compound (3), each of R^(f1) and R^(f2) which are independent ofeach other, is a C₁₋₈ perfluoroalkylene group which may have an ethericoxygen atom between carbon atoms. Number of carbon atoms in eachperfluoroalkylene group is more preferably from 1 to 6, particularlypreferably from 2 to 5. Further, when the number of carbon atoms in eachperfluoroalkylene group is at least 2, an etheric oxygen atom may becontained between the carbon atoms, and the number of the etheric oxygenatoms is preferably 1 or 2, particularly preferably 1. Further, eachperfluoroalkylene group is preferably linear or branched to have at mosttwo trifluoromethyl groups, particularly preferably linear. Moreover,R^(f1) and R^(f2) are preferably the same groups, but not so restricted.For example, R^(f1) and R^(f2) may be perfluoroalkylene groups differentin number of carbon atoms, and may be perfluoroalkylene groups such thatone has an etheric oxygen atom, and the other has no etheric oxygenatom.

Each of —R^(f1)—SO₂F and —R^(f2)—SO₂F in the compound (3) is preferablya group represented by the following formula (s-1). In the formula, p isan integer of at least 1, q is an integer of at least 1, p+q is from 2to 5, and r is 0 or 1. The group (s-1) preferably has p of from 1 to 3,q of 2 and r of 1, namely preferably is a perfluorinated2-fluorosulfonyl ethoxy group-substituted alkylene group (the alkylenegroup has 1 to 3 carbon atoms).

—(CF₂)_(p)—(O)_(r)—(CF₂)_(q)—SO₂F  (s-1)

Specific examples of the compound (3) are the following compounds:

The compound (3) of the present invention can be produced byheat-decomposing the following compound (2). R^(f1) and R^(f2) in thecompound (2) corresponding to R^(f1) and R^(f2) in the compound (3), areC₁₋₈ perfluoroalkylene groups which may have an etheric oxygen atombetween carbon atoms. Further, the compound (2) is a new compound.

The heat-decomposition of the compound (2) may be carried out inaccordance with a method described in the above Patent Document 2, 3 or4 such that by heat-decomposing a 1,3-dioxolane derivative having a —COFgroup and a trifluoromethyl group at the 2-position, a 1,3-dioxolanederivative having a difluoromethylene (═CF₂) group at the 2-position isproduced. A summary of the heat-decomposition of the compound (2) isdescribed as follows.

The heat-decomposition reaction can be carried out by a gas phasereaction or a liquid phase reaction, and it is preferably carried out bya gas phase reaction from the viewpoint of efficiency. Further, themethod for the heat-decomposition reaction and the reaction temperatureare preferably selected depending on the boiling point or stability ofthe compound (2). Further, the compound (2) preferably has a boilingpoint of at most 350° C. for such a reason that the heat-decompositionreaction can thereby be carried out efficiently by a gas phase reaction.Moreover, the gas phase reaction is preferably carried out in thepresence of glass beads, an alkali metal salt or an alkaline earth metalsalt.

The gas phase reaction is preferably carried out by a continuousreaction. The continuous reaction is preferably carried out by a processsuch that a vaporized compound (2) is let flow in a heated reactiontube, and a formed compound (3) is obtained as an outlet gas, followedby condensation to recover it continuously. When the heat-decompositionis carried out by a gas phase reaction, the reaction temperature ispreferably at least 150° C., particularly preferably from 200° C. to500° C., especially preferably from 250° C. to 450° C. If the reactiontemperature is too high, the yield tends to be low by a decompositionreaction of the product. Further, when the heat-decomposition reactionis carried out by a gas phase reaction, it is preferred to use atube-type reactor. When the tube-type reactor is used, the retentiontime is preferably approximately from 0.1 second to 10 minutes based ona void tower standard. The reaction pressure is not particularlylimited.

When the gas phase reaction is carried out by using the tube-typereactor, the reaction tube is preferably packed with glass, an alkalimetal salt or an alkaline earth metal salt, for a purpose ofaccelerating the reaction. The alkali metal salt or the alkaline earthmetal salt is preferably a carbonate or a fluoride. The glass may becommon soda glass, and particularly preferably glass bead havingincreased mobility.

With respect to the gas phase reaction, for a purpose of acceleratingthe vaporization of the compound (2), the reaction is preferably carriedout in the presence of an inert gas which does not get directly involvedin the heat-decomposition reaction. The inert gas may, for example, benitrogen, carbon dioxide, helium or argon. The concentration of thecompound (2) in the inert gas is preferably approximately from 0.01 to50 volt.

The heat-decomposition reaction can also be carried out after thecompound (2) is converted to alkali metal or alkaline earth metal saltof the corresponding carboxylic acid. In such a method, the compound (2)is led to alkali metal or alkaline earth metal salt of the correspondingcarboxylic acid in the presence of a solvent, by a reaction with acarbonate or a hydrogen carbonate of alkali metal or alkaline earthmetal, followed by removal of the solvent. In such a method, it ispossible to selectively lead a —COF group to a salt of carboxylic acidwithout hydrolyzing a —SO₂F group in the compound (2). The solvent maybe a nonpolar solvent or a polar solvent, and it is preferably a polarsolvent since the reaction can thereby be carried out at a lowtemperature. The heat-decomposition temperature of an alkali metal saltof the compound (2) is preferably from 100 to 300° C., particularlypreferably from 150 to 250° C. The heat-decomposition reaction via analkali metal salt is preferred since it can be carried out at a lowtemperature as compared with a heat-decomposition method in a gas phase.

The compound (2) can be produced in accordance with a method describedin the above Patent Document 2, 3 or 4. Such documents describe aprocess for producing a 1,3-dioxolane derivative (having one —SO₂Fgroup) having a —COF group and a trifluoromethyl group at the 2-positionfrom a starting material of a monoene having one —SO₂F group via a stepof epoxidation and a step of forming a 1,3-dioxolane ring. Further, in acase where the 1,3-dioxolane derivative obtained in the above step offorming a 1,3-dioxolane ring, has hydrogen atoms, the derivative issubsequently fluorinated to obtain a perfluorinated 1,3-dioxolanederivative which is then converted to a 1,3-dioxolane derivative (havingone —SO₂F group) having a —COF group and a trifluoromethyl group at the2-position. In the present invention, the compound (2) can be producedin the same manner from a starting material of a monoene having two—SO₂F groups.

The compound (2) is preferably produced from the compound (1)represented by the following formula via (a) a step of epoxidation, (b)a step of forming a dioxolane ring and (c) a step of fluorination. Now,such preferred process steps will be described. However, a process forproducing the compound (2) is by no means restricted thereto. Forexample, a starting material of a perfluorinated compound correspondingto the compound (a compound wherein all hydrogen atoms in the compound(1) are fluorine atoms) may be converted to a diketone through anepoxidation of an unsaturated group portion, followed by a reaction withhexafluoropropylene oxide to obtain a 1,4-dioxane ring compound inaccordance with a method disclosed in Patent Document 4. It is possibleto produce the compound (2) by heat-decomposing the obtained 1,4-dioxanering compound. Such a process does not require a step of fluorination.

In the above formula (1), each of R¹ and R² which are independent ofeach other, is a C₁₋₈ alkylene group which may have an etheric oxygenatom between carbon atoms and of which some or all of hydrogen atoms maybe substituted by fluorine atoms. Further, the compound (1) may be atrans-form or a cis-form. Each of such R¹ and R² is a groupcorresponding to the above R^(f1) or R^(f2), namely, it is the samegroup as the above R^(f1) or R^(f2), or a group to be converted to theabove R^(f1) or R^(f2) by fluorination. In the latter case, it ispreferably a group having the same structure as the above R^(f1) orR^(f2) except that some or all of fluorine atoms in the above R^(f1) orR^(f2) are substituted by hydrogen atoms, and particularly preferably agroup having both hydrogen atoms and fluorine atoms. The proportion ofthe number of the hydrogen atoms based on the total of hydrogen atomsand fluorine atoms in each of R¹ and R² is from 30 to 100%, particularlypreferably from 30 to 70%. Further, since R¹ and R² are groupscorresponding to the above R^(f1) and R^(f2), the preferred number ofcarbon atoms, number of etheric oxygen atoms or structure such as alinear structure, of R¹ and R² are the same as the above R^(f1) andR^(f2).

Each of —R¹—SO₂F and —R²—SO₂F in the compound (1) is preferably a grouprepresented by the following formula (s-2). In the following formula(s-2), X represents a hydrogen atom or a fluorine atom, and each X inthe formula may be different. Since R¹ and R² are groups correspondingto the above R^(f1) and R^(f2), p, q and r are the same as the abovegroup (s-1). The more preferred group represented by the followingformula (s-2) is a 2-fluorosulfonyl ethoxy group-substituted alkylenegroup represented by the following formula (s-3) (in the formula (s-3),p is from 1 to 3).

—(CX₂)_(p)—(O)_(r)—(CX₂)_(q)—SO₂F  (s-2)

—(CH₂)_(p)—O—(CF₂)₂—SO₂F  (s-3)

An embodiment of scheme for producing the compound (2) from the compound(1) represented by the following formula via (a) a step of epoxidation,(b) a step of forming a dioxolane ring and (c) a step of fluorination,is shown as follows. Here, the following compound (1) may be a cis-formor a trans-form, and the compound (1) used in Examples given hereinafterwas a transform.

In the above formula (13), R³ represents an alkyl group or apolyfluoroalkyl group which may contain an etheric oxygen atom betweencarbon atoms. The number of carbon atoms in R³ is properly from 1 to 20,preferably 3 to 12. R³ is particularly preferably a C₃₋₁₀ perfluoroalkylgroup or an etheric oxygen atom-containing perfluoroalkyl group having 3to 12 carbon atoms and 1 to 3 etheric oxygen atoms. R^(3′) in the aboveformula (14) is a group (a perfluorinated group) of which the hydrogenatoms are all substituted by fluorine atoms, provided that when R³ is agroup containing hydrogen atoms, or the 3, same group as R³ when R³ is agroup (a perfluorinated group) not containing hydrogen atoms. As R³ (thesame for R^(3′)), the following perfluorinated group is particularlypreferred:

—CF₂CF₂CF₃, —CF (CF₃)₂, —CF(CF₃)CF₂CF₃, —CF(CF₃)O(CF₂)₃F or—CF(CF₃)OCF₂CF(CF₃)O(CF₂)₃F.

(a) A step of epoxidation in the present invention is a step ofproducing a compound (11) from the compound (1) in the above scheme, andit includes an epoxidation reaction [a]. (b) A step of forming adioxolane ring is a step of producing a compound (13) from the compound(11) in the above scheme, and it includes a reaction [b-1] of forming adioxolane ring. The compound (13) is preferably produced by a reaction[b-2] of converting a side chain group via a compound (12), but it maybe produced directly from the compound (11). The reaction [b-2] ofconverting a side chain group is preferably a ketal exchange reaction.It is preferred to produce the compound (13) from the compound (11) bycarrying out the reaction [b-1] and the reaction [b-2] without isolatingthe compound (12). (c) A step of fluorination is a step of producing thecompound (2) from the compound (13) in the above scheme, and it includesa fluorination reaction [c-1]. The compound (2) is preferably producedby an ester-decomposition reaction [c-2] via a compound (14), but thecompound (2) may sometimes be obtained from the compound (13) when theester-decomposition reaction [c-2] proceeds simultaneously with thefluorination reaction [c-1]. It is preferred to carry out thefluorination reaction [c-1] and the ester-decomposition reaction [c-2]separately.

In (a) a step of epoxidation, the compound (11) is obtained by oxidizingthe compound (1) with an oxidizing agent. As the oxidizing agent, it ispossible to use oxygen gas, a hypochlorite or a peroxide. The peroxidemay, for example, be m-chloroperbenzoic acid, perbenzoic acid, peraceticacid or hydrogen peroxide. The epoxidation of an unsaturated group byusing such an oxidizing agent may be carried out by a known method.

In (b) a step of forming a dioxolane ring, the compound (12) issynthesized by reacting the compound (11) with acetone. At that time,instead of directly reacting the compound (11) with acetone, it ispossible to react water with the compound (11) to obtain a diol, andthen react such a diol with acetone to synthesize the compound (12).Such a reaction is preferably carried out in the presence of an acidcatalyst. The acid catalyst may, for example, be an inorganic acid, aLewis acid or a solid acid. Then, the compound (12) is reacted (reaction[b-2]) with hydroxyacetone ester represented by the following formula(15) to produce the compound (13). The reaction [b-2] is a ketalexchange reaction, wherein an acetone residue is converted to ahydroxyacetone ester (15) residue. Further, the compound (13) may alsobe produced in such a manner that the compound (12) is subjected to aketal exchange reaction with a hydroxyacetone to convert an acetoneresidue to a hydroxyacetone residue, and then its hydroxyl group isconverted to a R³COO— group. With respect to such a ketal exchangereaction, it is preferably carried out, in the presence of the aboveacid catalyst, by removing acetone which forms as a byproduct in a highboiling point solvent, from the reaction system. Further, it is possibleto sequentially carry out the reaction [b-1] and reaction [b-2] bychanging the reaction condition while the compound (11), acetone and thecompound (15) are permitted to coexist. Further, it is also possible toobtain the compound (13) by reacting the compound (11) or its diolcompound with hydroxyacetone ester (15).

In (c) a step of fluorination, first, all hydrogen atoms in the compound(13) are substituted by fluorine atoms by a fluorination reaction [c-1]to obtain the compound (14). A method for the fluorination reaction may,for example, be a method for a reaction with fluorine in a gas phase, ora method for a fluorination reaction carried out in a liquid phase suchas an electro-chemical fluorination method (ECF method) or a cobaltfluorination method. From the viewpoint of handling efficiency and theyield of the reaction, the fluorination carried out in a liquid phase isa particularly advantageous method, and a method of reacting thecompound (13) with fluorine (F₂) in a liquid phase (namely, a methodso-called a liquid phase fluorination) is particularly preferred.Details of the liquid phase fluorination are described not only in theabove Patent Document 2, but also in WO00/056694, etc.

In the liquid phase fluorination, as fluorine, it is possible to usefluorine gas as it is or fluorine gas diluted by an inert gas such asnitrogen gas. The amount of fluorine in an inert gas is preferably atleast 10 volt, particularly preferably at least 20 volt.

In the liquid phase fluorination, a solvent is usually used in order toform a liquid phase. The solvent is preferably a solvent which does notcontain a C—H bond and essentially contains a C—F bond, or a fluorinatedsolvent having at least one atom selected from a group consisting of achlorine atom, a nitrogen atom or an oxygen atom, in the structure andcontaining no C—H bond (hereinafter such a fluorine type solventincluding a perfluoroalkane is referred to as a perfluoro-solvent). Thesolvent may be a solvent inactive in the fluorination reaction, and itmay have a functional group active in other reactions. For example, itis possible to use, as a solvent, a perfluoroether or a perfluoroalkanehaving a fluorocarbonyl group (—COF group). Further, as the solvent, itis preferred to use a solvent presenting a high solubility for thecompound (13). Especially, it is preferred to use a solvent which candissolve at least 1 mass % of the compound (13), particularly preferredto use a solvent which can dissolve at least 5 mass %. Further, theamount of the solvent is preferably at least 5 times by mass,particularly preferably from 10 to 100 times by mass, based on thecompound (13).

The reaction style of the liquid phase fluorination reaction may be abatch system or a continuous system. Particularly, it is preferred tocarry out the fluorination in such a manner that a solvent is charged ina reactor, and stirring is started, and after the reaction temperatureand the reaction pressure are controlled at prescribed levels, thefluorine gas and the compound (13) are continuously and simultaneouslysupplied in a prescribed molar ratio.

The amount of fluorine to be used for the liquid phase fluorination ispreferably constantly in excess by equivalent relative to hydrogen atomsto be fluorinated, particularly preferably at least 1.5 times byequivalent (namely, at least 1.5 mol) from the viewpoint of selectivity,when the reaction is carried out either by a batch system or acontinuous system. Further, the amount of fluorine is preferably kept tobe constantly in excess by equivalent from the beginning of the reactionto the end of the reaction.

The reaction temperature for the liquid phase fluorination is usuallypreferably at least −60° C. and at most the boiling point of thecompound (13), particularly preferably from −50° C. to +100° C. from theviewpoint of the reaction yield, selectivity and industrial operationefficiency, particularly preferably from −20° C. to +50° C. The reactionpressure for the liquid phase fluorination is not particularly limited,and it is particularly preferably from a normal pressure to 2 MPa fromthe viewpoint of the reaction yield, selectivity and industrialoperation efficiency.

Further, in order to let the liquid phase fluorination efficientlyproceed, it is preferred to add a C—H bond-containing compound in thereaction system at a late stage of the reaction or to carry outultraviolet irradiation. By using the C—H bond-containing compound, itis possible to efficiently fluorinate the compound (13) present in thereaction system, and it is possible to improve the reaction ratesignificantly. The C—H bond-containing compound is an organic compoundother than the compound (13), and specifically, it is preferably anaromatic hydrocarbon, particularly preferably benzene or toluene. Theamount of the C—H bond-containing compound to be added is preferablyfrom 0.1 to 10 mol %, particularly preferably from 0.1 to 5 mol %, basedon hydrogen atoms in the compound (13).

HF which forms as a byproduct in the liquid phase fluorination isremoved by an HF capture agent such as NaF, and the product and thesolvent are separated to obtain the compound (14) as a product. Thecompound (14) obtained by the fluorination may be subjected to anester-decomposition reaction [c-2] as it is in the form of a crudeproduct, or may be subjected to an ester-decomposition reaction [c-2]after purification.

The ester-decomposition reaction [c-2] of the compound (14) ispreferably carried out by a decomposition reaction by heat or adecomposition reaction to be carried out in a liquid phase in thepresence of a nucleophilic agent or an electrophile.

The decomposition reaction by heat can be carried out by heating thecompound (14). The reaction temperature of the gas phaseheat-decomposition reaction is preferably from 50 to 350° C.,particularly preferably from 50 to 300° C., particularly preferably from150 to 250° C. Further, it is permitted to let coexist an inert gas suchas nitrogen which does not get directly involved with the reaction, inthe reaction system. It is preferred to add the inert gas approximatelyfrom 0.01 to 50 vol % based on the compound (14). If the amount of theinert gas to be added is large, the recovered amount of the product maysometimes be lowered.

It is also possible to use a liquid phase heat-decomposition reactionwhich heats up the compound (14) in a liquid state in the reactor. Insuch a case, the reaction pressure is not limited. In a usual case,since the product containing the compound (2) has a lower boiling pointthan the compound (14), the product is preferably obtained by a methodof a reaction distillation system wherein the product is vaporized andcontinuously withdrawn. Further, it may be obtained by a method whereinafter the completion of heating, the product is withdrawn from thereactor all at once. The reaction temperature of such a liquid phaseheat-decomposition reaction is preferably from 50 to 300° C.,particularly preferably from 100 to 250° C.

The liquid phase heat-decomposition reaction may be carried out in thepresence or absence of a solvent. The solvent is not particularlylimited as long as it is one which does not react with the compound(14), has a compatibility with the compound (14) and does not react withthe compound (2) to be formed. Further, as the solvent, it is preferredto select one easily separable at the time of purification of thecompound (2). Specific examples of the solvent may be a perfluorinatedsolvent such as perfluorotrialkylamine or perfluorodecaline, and afluorinated inactive solvent such as chlorotrifluoroethylene oligomer.Further, the amount of the solvent is preferably from 10 to 1,000 mass %based on the compound (14).

Further, the compound (14) can be subjected to an ester-decomposition bya reaction with a nucleophilic agent or an electrophile in a liquidphase in the absence of a solvent or in the presence of the abovefluorinated inactive solvent. Particularly, it is preferred that thecompound is subjected to the ester-decomposition by a reaction with thenucleophilic agent. The nucleophilic agent is preferably F⁻,particularly preferably F⁻ derived from a fluoride of an alkali metal.The fluoride of an alkali metal is preferably NaF, NaHF₂, KF or CsF.Among them, NaF is particularly preferred from the viewpoint of economicefficiency, and KF is particularly preferred from the viewpoint that thereaction can be carried out at a low reaction temperature. When thenucleophilic agent (e.g. F⁻) is used, the nucleophilic agent used at thebeginning of the reaction may be in a is catalytic amount and may beused excessively. That is, the amount of the nucleophilic agent such asF⁻ is preferably from 1 to 500 mol %, particularly preferably from 1 to100 mol %, especially preferably from 5 to 50 mol %, based on thecompound (14). The reaction temperature is preferably from −30° C. tothe boiling point of the solvent or the compound (14), particularlypreferably from −20° C. to 250° C. This method is also preferablycarried out by a reaction distillation system.

The compound (1) as a starting material in the above process can beproduced by a known method or in accordance with a known method. Forexample, in the above Patent Document 2, it is disclosed that an alkenylcompound having a —SO₂F group is obtained by reacting a bromoalkene withtetrafluoroethane-1,2-sulfone (hereinafter referred to simply assulfone). Accordingly, it is possible to obtain a compound (1) as anunsaturated compound having two —SO₂F groups by reacting dibromoalkenewith sulfone. Further, the above Patent Document 3 discloses a processto obtain an alkenyl compound having a —SO₂F group from an alkenylalcohol via an alkenyl compound having a —SO₂(OZ) group (Z: alkalimetal). Accordingly, it is possible to obtain a compound (1) as anunsaturated compound having two —SO₂F groups from an alkenediol via anunsaturated compound having two —SO₂ (OZ) groups (Z: alkali metal). Aspecific example of such a method may be a method to obtain a compound(1) having a group (s-3) represented by the following formula (1a) by areaction of a compound represented by the following formula (10a) withsulfone represented by the formula (10b). Further, as mentioned above,the compound (10a) or the compound (1a) may be a cis-form or atrans-form, and in the Examples given hereinafter, the trans-form isused.

The present invention is a fluorosulfonyl group-containing polymercomprising at least one type of monomer units represented by thefollowing formula (3U) or at least one type of such monomer units and atleast one type of other monomer units. The monomer units (3U) aremonomer units formed by polymerization of the compound (3). R^(f1) andR^(f2) in the monomer unit (3U) are the same as R^(f1) and R^(f2) in thecompound (3).

The polymer having the monomer units (3U) (namely, a polymer (3U)) isuseful as a precursor of an electrolyte material to be used for anapplication to a brine electrolysis or a fuel cell. For example, afluorosulfonyl group-containing polymer as a homopolymer or copolymer ofthe compound (3) is useful as a precursor of a sulfonic acid polymerhaving a high molecular weight and a high ion-exchange capacity. Such acopolymer may be obtained by copolymerizing the compound (3) withanother polymerizable monomer (hereinafter referred to as a comonomer)copolymerizable with the compound (3). The comonomer may be one type orat least two types.

The comonomer may, for example, be a perfluoromonomer such astetrafluoroethylene, a perfluoro(α-olefin) such as hexafluoropropene, aperfluorodiene such as perfluoro(3-butenyl vinyl ether), perfluoro(allylvinyl ether) or perfluoro(3,5-dioxa-1,6-heptadiene), a perfluorinatedcyclic monomer such as perfluoro(2,2-dimethyl-1,3-dioxole),perfluoro(1,3-dioxole), perfluoro(2-methylene-4-methyl-1,3-dioxolane) orperfluoro(4-methoxy-1,3-dioxole), or perfluorovinyl ether such asperfluoro(alkyl vinyl ether) or perfluoro(alkoxyalkyl vinyl ether).

Further, as the comonomer, it is possible to use a comonomer other thana perfluoromonomer, which may be copolymerized with the compound (3)alone or may be copolymerized with the compound (3) together with theabove exemplified comonomer. Specifically, such a comonomer may, forexample, be a fluoroolefin such as trifluoroethylene,chlorotrifluoroethylene, vinylidene fluoride or vinyl fluoride, anolefin such as ethylene or propene, a (perfluoroalkyl)ethylene such as(perfluorobutyl)ethylene, or a (perfluoroalkyl)propene such as3-perfluorooctyl-1-propene. Further, it is possible to use, as acomonomer, a monomer having a —SO₂F group other than the compound (3),particularly a perfluorinated monomer having a —SO₂F group.

The polymerization reaction is not particularly limited as long as it iscarried out under such a condition that radicals are produced. Forexample, it may be carried out by bulk polymerization, solutionpolymerization, suspension polymerization, emulsion polymerization, orpolymerization in a liquid or supercritical carbon dioxide.

A method for producing radicals is not particularly limited. Forexample, it is possible to use a method of irradiating radioactive rayssuch as ultraviolet rays, γ-rays or electron rays, and it is alsopossible to use a method of using a radical initiator usually used inradical polymerization. The reaction temperature for the polymerizationreaction is not particularly limited, and for example, it is usuallyfrom 15 to 150° C. In a case where a radical initiator is used, theradical initiator may, for example, be a bis(fluoroacyl)peroxide, abis(chlorofluoroacyl)peroxide, a dialkyl peroxy carbonate, a diacylperoxide, a peroxyester, an azo compound or a persulfate.

When solution polymerization is to be carried out, a solvent to be usedusually preferably has a boiling point of from 20 to 350° C., morepreferably from 40 to 150° C. from the viewpoint of handling efficiency.As the solvent, a solvent is used wherein growing radicals for thepolymerization will cause no or little chain transfer reaction to thesolvent. Such a solvent is preferably a fluorinated solvent which isusually used for polymerization of a fluorinated monomer. For example,it may be a hydrofluorocarbon, a hydrochlorofluorocarbon, achlorofluorocarbon, a perfluorocarbon, a polyfluorodialkyl ether, apolyfluorinated cyclic ether or a polyfluorotrialkylamine.

Further, it is possible to carry out polymerization by using a chaintransfer agent to adjust the molecular weight. The chain transfer agentmay, for example, be an alcohol such as methanol or ethanol, the abovefluorinated solvent such as a hydrochlorofluorocarbon which functionsalso as a chain transfer agent, or a hydrocarbon such as pentane, hexaneor cyclohexane.

The molecular weight of the polymer (3U) (namely, a homopolymer orcopolymer having monomer units (3U)) is preferably from 5×10³ to 5×10⁶,particularly preferably from 1×10⁴ to 3×10⁶. When comonomer units arecontained, it is preferred to contain the monomer units (3U) in aproportion of from 0.1 to 99.9 mol % based on the total of monomerunits. The proportion of the monomer units (3U) is particularlypreferably from 5 to 90 mol %, especially preferably from 10 to 75 mol%.

The copolymer in the polymer (3U) is particularly useful for anapplication to a precursor of an electrolyte material for a brineelectrolysis or a fuel cell. Further, when the copolymer is used for anapplication to a brine electrolysis or a fuel cell, the comonomer ispreferably selected from perfluorinated comonomers from the viewpoint ofdurability. The comonomer is preferably a perfluoroolefin such astetrafluoroethylene or a perfluoro(alkyl vinyl ether), especiallypreferably a tetrafluoroethylene.

A sulfonic acid polymer useful as an electrolyte material for a brineelectrolysis or a fuel cell, can be produced by subjecting afluorosulfonyl group of a polymer (3U) to alkali hydrolysis, oracid-treatment after such alkali hydrolysis. The sulfonic acid polymerto be obtained is a polymer containing units represented by thefollowing formula (4U). However, the sulfonic acid polymer to beobtained may contain units wherein only one —SO₂F group of the monomerunit (3U) is converted to a —SO₃M group, or it may contain a smallamount of unreacted monomer unit (3U). M in the following formula (4U)represents a hydrogen atom or a counter ion. Further, a polymer havingthe following units (4U) will be referred to also as a polymer (4U).

The molecular weight of the polymer (4U) (namely, a homopolymer or acopolymer having units (4U)) is preferably from 5×10³ to 5×10⁶,particularly preferably from 1×10⁴ to 3×10⁶. When the comonomer unitsare contained, the units (4U) are preferably contained in a proportionof 0.1 to 99.9 mol % based on the total monomer units. The proportion ofthe units (4U) is particularly preferably from 5 to 90 mol %, especiallypreferably from 10 to 75 mol %.

In alkali hydrolysis of the polymer (3U), it is preferred to use analkali metal hydroxide or an alkali metal carbonate. It is also possibleto use a compound represented by a formula NR¹R²R³R⁴(OH) (wherein eachof R¹ to R⁴ which are independent of each other, is a hydrogen atom or aC₁₋₅ alkyl group). In acid-treatment, it is preferred to usehydrochloric acid, nitric acid or sulfuric acid. Consequently, afluorosulfonyl group can be converted to a sulfonate (—SO₃M¹ group:wherein M¹ represents a counter ion). Here, M¹ is preferably an alkalimetal ion or a N⁺R¹R²R³R⁴. The alkali metal ion is preferably a sodiumion, a potassium ion or a lithium ion. Further, N⁺R¹R²R³R⁴ is preferablyN⁺(CH₃)₄, N⁺(CH₂CH₃)₄, N⁺(CH₂CH₂CH₃)₄ or N⁺(CH₂CH₂CH₂CH₃)₄.

It is preferred to obtain a polymer wherein M¹ in the sulfonate group isan alkali metal ion, by reacting a sulfonic acid group-containingpolymer with an alkali metal hydroxide. Further, it is preferred toobtain a polymer wherein M¹ in the sulfonate group is N⁺R¹R²R³R⁴, byreacting a fluorosulfonyl group-containing polymer with a compoundrepresented by the formula NR¹R²R³R⁴(OH). Further, the sulfonategroup-containing polymer obtained by hydrolysis can be converted to haveother counter ions by immersing the polymer in an aqueous solutioncontaining ions which can be counter ions different from M¹. Further,the sulfonate group (—SO₃M¹ group) can be converted to a sulfonic acidgroup (—SO₃H group) by treatment with an acid such as hydrochloric acid,nitric acid or sulfuric acid. A method for converting such groups may becarried out in accordance with a known method and conditions.

The present invention is a sulfonic acid group-containing polymercontaining at least one type of units represented by the followingformula (5U) or at least one type of such units and at least one type ofother units. Each of R^(f1) and R^(f2) in the following formula (5U) isthe same as the above perfluoroalkylene group. Such a polymer (5U) hasits molecular weight of from 5×10³ to 5×10⁶, and when other units arecontained, units is represented by the formula (5U) are preferablycontained in an amount of from 0.1 to 99.9 mol %.

The sulfonic acid group-containing polymer (5U) is particularly suitableas an electrolyte material for a polymer electrolyte fuel cell.

The polymer (3U) of the present invention is excellent in adhesion withother substrates. Further, it has a low refractive index as comparedwith a hydrocarbon type polymer, and it has a high refractive index ascompared with a perfluoropolymer having no functional groups, whereby itis also useful as an optical material. Further, the polymer (4U) or thepolymer (5U) obtainable by the process of the present invention are notlimited in their application to an electrolyte material for a brineelectrolysis or a fuel cell, and it is possible to use them for variousapplications as solid electrolyte materials. For example, such polymersmay be used for a proton permselective membrane to be used for waterelectrolysis, hydrogen peroxide production, ozone production or wasteacid recovery, or may be used for a cation exchange membrane forelectrodialysis to be used for desalination or salt production. Further,they may also be used for a polymer electrolyte for a lithium ion cell,a solid acid catalyst, a cation exchange resin, a sensor using modifiedelectrodes, an ion exchange filter for removing a trace amount of ionsin an air, or an actuator. That is, the polymer (4U) may be used as amaterial for various electrochemical processes. Further, the polymer(4U) may be used for a membrane for diffusion dialysis to be used forseparation and purification of an acid, a base or a salt, a chargedporous membrane for protein separation (e.g. a charged reverse osmosismembrane, a charged ultrafiltration membrane or a chargedmicrofiltration membrane), a dehumidifying membrane or a humidifyingmembrane.

EXAMPLES

Now, the present invention will be described in further detail withreference to Examples, but it should be understood that the presentinvention is by no means restricted thereto. The compounds and thereaction conditions used for a reaction scheme described in each Exampleare shown. Further, abbreviations described in each Example are thefollowing.

GC: Gas chromatograph

GPC: Gel permeation chromatograph

HCFC 225: Fluorinated solvent. A mixture ofCF₃CF₂CHCl₂/CClF₂CF₂CHClF=45/55 (mass ratio).

HCFC 225cb: Fluorinated solvent. CClF₂CF₂CHClF.

R 113: Fluorinated solvent. CCl₂FCClF₂.

BF₃.OEt₂: Boron trifluoride ether complex

Example 1

A 5 L 4-necked flask was equipped with a thermometer, a Dimrothcondenser and a stirrer. Under an atmosphere of nitrogen, 1,800 ml ofdiglyme was added. Then, AgF (593 g, 4.68 mol) was added with stirring.A reactor was equipped with a dropping funnel, and the reactor wascooled in an ice bath until its inner temperature became at most 10° C.While maintaining the inner temperature of at most 10° C., sulfone (10b)(843 g, 4.68 mol) was dropped from a dropping funnel over a period of 2hours, followed by stirring for 1 hour in a water bath.

Again, the reactor was cooled in an ice bath, and while maintaining theinner temperature of at most 10° C., trans-1,3-dibromo-2-butene (10a-1)(500 g, 2.34 mol) dissolved in 500 g of diglyme was dropped from adropping funnel over a period of 1.5 hours. After the dropping, stirringwas continuously carried out for 11 hours. When the crude liquid of thereaction was subjected to a GC analysis, it was confirmed that thereaction was almost finished.

The crude liquid of the reaction was subjected to suction filtration byusing celite. The filtrate was transferred to a 5 L 4-necked flask, andunder a reduced is pressure, the solvent was distilled off by heating.1,067 g of the content remained in the flask. 3,200 g of deionized waterwas added thereto, followed by stirring for 15 minutes for water-washingtreatment. 863 g (GC: 73.66%) of the lower layer was recovered by aseparating funnel. After the filtration with sea sand, the recoveredliquid was dried with magnesium sulfate.

500 g of a compound (1-1) was obtained by distillation. The boilingpoint 137 to 140° C./0.27 to 0.40 kPa. Yield 47%.

¹H-NMR (300.4 MHz, solvent: CDCl₃) δ (ppm): 6.0 (m, 2H), 4.7 (m, 4H).

¹⁹F-NMR (282.7 MHz, solvent: CDCl₃, standard: CFCl₃) δ (ppm): 43.6 (2F),−84.1 (4F), −111.5 (4F).

Example 2

A 5 L 4-necked flask was equipped with a thermometer, a Dimrothcondenser and a stirrer. Under an atmosphere of nitrogen, the compound(1-1) (475 g, 1.05 mol), 2,800 g of 1,2-dichloroethane and 352 g ofm-chloroperbenzoic acid (m-CPBA) (purity >65%) were added, and refluxwas carried out for 7 hours. When the mixture was subjected to a GCanalysis, the degree of conversion was 36.4%. 1,029 g of1,2-dichloroethane and 352 g of M-CPBA (purity >65%) were further addedinto a reactor, and reflux was carried out for 31 hours. The degree ofconversion was 94.6%.

The crude liquid of the reaction was filtrated to recover 5,132 g. Itwas washed twice with a saturated sodium carbonate aqueous solution andwith 4.8 mol/l of a sodium chloride aqueous solution, and it wassubjected to liquid separation to obtain 4,859 g of a crude liquid ofthe reaction.

Such a crude liquid was dried over sodium sulfate and filtrated, andthen it was concentrated by an evaporator and dried to obtain 400 g of acompound (11-1).

¹H-NMR (300.4 MHz, solvent: CDCl₃) δ (ppm): 4.3 (m, 2H), 4.2 (m, 2H),2.2 (m), 3.3 (m, 2H).

¹⁹F-NMR (282.7 MHz, solvent; CDCl₃, standard: CFCl₃) δ (ppm): 43.6 (2F),−84.3 (4F), −111.5 (4F).

Example 3

Acetonide Formation

A 1 L 4-necked flask was equipped with a thermometer, a stirrer and aDean-Stark trap. Under an atmosphere of nitrogen, 71.32 g (152.3 mmol)of the compound (11-1), 263 g of dried acetone, 290 g of dried toluene,58.77 g (152.2 mmol) of a compound (15-1) and BF₃.OEt₂ (2.67 g, 18.8mmol) were sequentially added.

The reactor was heated in an oil bath and heated to the innertemperature of 90° C. under a normal pressure to distill 300 ml of thesolvent. Then, stirring was carried out for 4 hours at the innertemperature of 100° C. The degree of conversion analyzed by gaschromatograph was 97%.

Ketal Exchange

The Dean-Stark trap was removed from the flask and a simple distillationdevice was attached thereto. It was heated to the inner temperature of90° C. at 33 kPa to distill 239 g of toluene. Into the reactor, BF₃.OEt₂(1.33 g, 9.37 mmol) was added, and a reaction was carried out at 40 kPaat the inner temperature of 90° C. for 2.5 hours. Further, into thereactor, BF₃.OEt₂ (1.39 g, 9.79 mmol) was added, and a reaction wascarried out at 40 kPa at the inner temperature of 90° C. for 2 hours toobtain 141.82 g of a reaction crude liquid of a compound (13-1). Thedegree of conversion was 96.4%.

In the same manner, 822.6 g (degree of conversion: 93.9%) of thereaction crude liquid of the compound (13-1) was obtained from 328.24 g(701 mmol) of the compound (11-1).

Two of the above reaction crude liquid were combined and heated to theinner temperature of 100° C. at 40 kPa. Then, the pressure was graduallydecreased to 0.13 kPa. After that, when the content became bubbly at theinner temperature of 107° C. by heating, the operation to distill offlow-boiling components was stopped. The content in the flask was 709 g.

A silica gel (“silica gel 60”, spherical shape, supplied by KantoChemical Co., Inc.) was used for a stationary phase, and hexane and HCFC225 were used for a mobile phase to carry out column purification,whereby 343.7 g of the compound (13-1) was obtained.

¹H-NMR (300.4 MHz, solvent: CDCl₃) δ (ppm): 4.55 (m, 2H), 4.44 to 4.14(m, 6H), 1.50 (s), 1.44 (s), (3H by combining 1.50 ppm and 1.44 ppm).

¹⁹F-NMR (282.7 MHz, solvent: CDCl₃, standard: CFCl₃) δ (ppm): 43.5 (2F),−80.5 (1F), −81.8 (3F), −82.6 (3F), −85.3 (4F), −86.8 (1F), −111.7 (4F),−130.2 (2F), −132.5 (1).

Example 4

Into a stainless steel autoclave (inner volume: 3,000 mL), 4,200 g ofCF₃CF₂CF₂OCF(CF₃)CF₂OCF(CF₃)COF (hereinafter referred to as an inactivefluid A) was introduced. As a transport device, a bellows pump having anability of 300 L/Hr was used to circulate the inactive fluid A. Byadjusting the amount of the refrigerant to flow through a heat exchangerprovided in the middle of a circulation path, the temperature of theinactive fluid A in the autoclave was maintained at 20° C. A fluorinegas diluted to 25% with a nitrogen gas (hereinafter referred to as a 25diluted fluorine gas) was continuously supplied from a stainless steelejector provided in the pipe in a circulation path at a flow rate of81.1 L/h. While maintaining the above conditions, the circulation wascarried out for 1 hour.

Then, 300 g (0.29 mol) of the compound (13-1) was dissolved in R 113(300 g), and the mixture was continuously supplied through a rawmaterial supplying pipe provided in the middle of the circulation pathwith a flow amount of 56 g/h. Further, the inactive liquid containing afluorinated compound was continuously withdrawn to make the volume ofthe liquid in the autoclave be approximately constant. As a result ofsubjecting the withdrawn crude liquid to a GC analysis, no presence ofthe compound (13-1) was confirmed in the inactive liquid.

The fluorinated product is an inactive liquid, and as the reactionproceeded, the circulating inactive fluid A was gradually replaced bythe fluorinated product (compound (14-1)), whereby the circulatinginactive fluid A was changed to a mixture of the inactive fluid A andthe fluorinated product (compound (14-1)). Further, since the inactivefluid A and the fluorinated product (compound (14-1)) are the compoundshaving different boiling points, it is possible to easily separate themby distillation.

After supplying the entire solution of the compound (13-1), a 25%diluted fluorine gas was supplied for 48.5 hours. Further, only anitrogen gas was blown in for 0.5 hour, and a crude liquid of thereaction was withdrawn. The total amount of the recovered crude liquidwas 4,409 g. The obtained crude liquid was put in a flask, followed byheating and stirring under a reduced pressure, whereby it was possibleto recover 331 g of a solution having the fluorinated product (compound(14-1)) as a main component (hereinafter referred to as a fluorinatedcrude liquid B).

Then, 230 g of the above fluorinated crude liquid B was dissolved inR113 (230 g), and the mixture was introduced in an autoclave (500 mL,made of nickel) followed by stirring, and it was maintained at 25° C. Atthe gas outlet of the autoclave, a condenser kept at 20° C., a NaFpellet-packed bed and a condenser kept at −10° C. were set in series.Further, a liquid-returning line was set to return the condensed liquidfrom the condenser kept at −10° C., to the autoclave. After a nitrogengas was blown in for 1 hour, a fluorine gas diluted to 20% with anitrogen gas (hereinafter referred to as 20% fluorine gas) was blown inat 11.4 NL/h.

Then, the temperature of the reaction solution was raised from 25° C. to40° C., and with the 20% fluorine gas being blown in at the sameconstant flow rate into the autoclave, 9 ml of R 113 solution having abenzene concentration of 0.012 g/mL was injected, and the benzeneinjection inlet of the autoclave was closed, followed by stirring for0.4 hour. 6 ml of the above benzene solution was injected, and thebenzene injection inlet of the autoclave was closed, followed bystirring for 0.4 hour. Further, the same operation was repeated for 22times. The total injected amount of benzene was 1.9 g and the totalinjected amount of R 113 was 153 ml.

Further, a nitrogen gas was blown in for 1 hour. When the object wasquantified by ¹⁹F-NMR, formation of the compound (14-1) was confirmed,and as a result of the ¹⁹F-NMR analysis, it was confirmed that thecompound was contained in a yield of 97%.

A reaction was carried out in the same manner with respect to theremaining fluorinated crude liquid B. Two of the reaction liquids werecombined, and the solvent was distilled off to obtain 304 g of thecompound (14-1).

¹⁹F-NMR (282.7 MHz, solvent CDCl₃, standard: CFCl₃) δ (ppm): 45.5 (2F),−80.0 to −82.0 (18F), −84.6 to −87.5 (3F), −112.5 (4F), −113.0 to −123.0(2F), −130.3 (2F), −132.1 (1F).

Example 5

A stirring bar was put in a 500 mL 4-necked flask provided with athermometer, and a distillation device was attached thereto. Under anatmosphere of nitrogen, 304 g of the compound (14-1) was introduced.Then, 3.36 g of KF (0.06 mol, “Chloro-catch F”, manufactured by MORITACHEMICAL INDUSTRIES, CO., LTD.) was added with stirring, followed bygradual heating in an oil bath. At the inner temperature of 87° C.,CF₃CF₂CF₂OCF(CF₃)COF started to be distilled. When the inner temperaturereached 110° C. taking over a period of 2 hours, the inner temperaturewas kept at that level for 1 hour. Once it was cooled down, thedistillation under a reduced pressure was carried out to obtain 176 g ofa compound (2-1). The boiling point 117 to 144° C./0.67 to 0.80 kPa.

¹⁹F-NMR (282.7 MHz, solvent CDCl₃, standard: CFCl₃) δ (ppm): 45.6 (2F),27.2, 26.0, 25.0 (1F by combining 3 peaks), −80.1 to −81.8 (7F), −82.2(4F), −112.5 (4F), −118.7, −119.4, −123.8, −129.4 (2F by combining 4peaks).

Example 6

Into a tube reactor (made of inconel) having an inner diameter of 1.6μm, glass beads (central particle size of from 105 to 125 μm, glass bead#150, manufactured by GAKUNAN KOHKI CO., LTD.) were filled until thefilled height reached 40 cm, and then the tube reactor was heated to325° C. while continuously heating the tube reactor, a gas mixturecomprising 99 mol % of nitrogen gas and 1 mol % of vaporized gas of thecompound (2-1) preliminary heated in the raw material line, wasintroduced from the bottom of the tube reactor in such a manner that thelinear speed of the gas mixture in the tube reactor would be 2.65 cm/s.Further, at the top end of the tube reactor, a dry ice trap was set up.In such a state, the above gas mixture was supplied for 2 hours, andthen only nitrogen gas was let flow through for 1 hour. The amount ofthe compound (2-1) introduced in the tube reactor was 3.96 g.

As a result of a GC analysis of the liquid (2.45 g) recovered in the dryice trap, no raw material compound was confirmed, and the presence ofthe desired product having a purity of 85.5% was confirmed. The actualyield of the compound (3-1) was 60% taking into the consideration of therecovery rate of the above liquid. By distilling the heat-decompositioncrude liquid obtained in the same manner, the objective compound (3-1)(a mixture of anti-form and syn-form) was obtained. The boiling pointwas from 99 to 102° C./0.40 to 0.53 kPa.

¹⁹F-NMR of the anti-form (282.7 MHz, solvent CDCl₃, standard: CFCl₃) δ(ppm): 45.4 (2F), −81.6 (4F), −82.4 (4F), −112.6 (4F), −124.7 (2F),−128.2 (2F).

¹⁹F-NMR of the syn-form (282.7 MHz, solvent CDCl₃, standard: CFCl₃) δ(ppm): 45.5 (2F), −81.8 (4F), −82.4 (4F), −112.6 (4F), −124.9 (2F),−127.3 (2F).

When the ratio between the anti-form and the syn-form was obtained fromNMR, the ratio was such that anti-form:syn-form=3.3:1.0.

Example 7 Synthesis of Polymer

Into an autoclave (inner volume of 30 cm³, made of stainless steel),1.33 g of the compound (3-1), 18.52 g of HCFC 225cb, 5.51 mg of methanoland 0.90 mg of peroyl IPP (diisopropyl peroxydicarbonate) wereintroduced, followed by cooling with liquid nitrogen and degassing. Theinner temperature was increased to 40° C., and tetrafluoroethylene wasintroduced into the autoclave all at once at the initial stage. Thepressure was adjusted to 0.49 MPa (gauge pressure). While maintainingthe temperature to be constant, polymerization was carried out for 8hours. The pressure at the completion of polymerization was 0.41 MPaG.The inside of the autoclave was cooled down to stop the polymerization,and the gas inside the system was purged.

After diluting the reaction liquid with HCFC 225cb, hexane was added,and a polymer was agglomerated and filtrated. After that, the polymerwas stirred in HCFC 225cb, and it was reagglomerated by hexane. It wasdried under reduced pressure over night at 80° C., to obtain 0.76 g ofthe polymer.

The content of monomer units of compound (3-1) obtained by fluorescentX-rays was 14.1 mol %, and the ion-exchange capacity was 1.58 meq/g. Themolecular weight calculated as polystyrene, obtained by GPC was1,100,000.

Example 8 Synthesis of Acid Type Polymer and Evaluation of PhysicalProperty

The polymer obtained in Example 7 was subjected to press molding at 300°C. and was processed into a film (film thickness; approximately 100 μm).Then, into an aqueous solution containing 30 mass % of dimethylsulfoxideand 15 mass % of KOH, the polymer film was immersed at 80° C. for 16hours, whereby a —SO₂F group in the polymer film was hydrolyzed andconverted to a —SO₃K group.

Further, the polymer film was immersed in a 3 mol/L hydrochloric acidaqueous solution at 50° C. for 2 hours, and then the hydrochloric acidwas changed. Such acid treatment was repeatedly carried out 4 times. Itwas sufficiently washed with deionized water, and a polymer film havinga —SO₃K group in the polymer film converted to a —SO₃H group, wasobtained.

The measurement of the softening temperature was carried out as follows.By using a dynamic viscoelasticity measuring device DVA200 (manufacturedby ITK Co., Ltd.), the dynamic viscoelasticity of the above acid typefilm was carried out with a sample width of 0.5 cm, a length betweenchucks of 2 cm, a measuring frequency of 1 Hz and a rate of temperatureincrease of 2° C./min, and a temperature at which the elastic modulusbecame a half of the value at 50° C., was taken as a softeningtemperature. The softening temperature of the above acid type polymerwas 117° C. Further, in the measurement of the dynamic viscoelasticity,the glass transition temperature (Tg) obtained from the peak value oftan δ was 158° C.

The specific resistance was measured by a known 4-terminal method andunder a condition of constant temperature and humidity such as 80° C.and 95% RH with AC of 10 kHz and 1 V, wherein to a film having a widthof 5 mm, a substrate having 4-terminal electrodes disposed every 5 mmwas closely contacted. The specific resistance of the above acid typefilm was 2.2 Ω·cm.

COMPARATIVE EXAMPLE

With respect to a film of a copolymer (ion exchange capacity: 1.10meq/g, T_(Q) 225° C.) of tetrafluoroethylene andCF₂═CFOCF₂CF(CF₃)OCF₂CF₂SO₂F converted to an acid-type, the physicalproperties were measured in the same manner as Example 8. The softeningtemperature and Tg were respectively 76° C. and 109° C. The specificresistance was 3.6 Ω/cm. Further, T_(Q) value (unit: ° C.) of the abovecopolymer is an index for a molecular weight, and it is a temperature atwhich the extrusion amount would be 100 mm³/sec when melt extrusion of apolymer is carried out by using a nozzle having a length of 1 mm and aninner diameter of 1 mm and under a condition of an extrusion pressure of2.94 MPa. By using a flow tester CFT-500A (manufactured by ShimadzuCorporation), the extrusion amount was measured by changing thetemperature, and the T_(Q) value at which the extrusion amount became100 mm³/sec, was obtained.

The —SO₂F group-containing polymer obtained by polymerizing the compoundof the present invention is useful for an application as a precursor ofan electrolyte material. That is, by hydrolyzing a —SO₂F group of such apolymer, it is possible to obtain a polymer having a —SO₃H group, andthe polymer having such a —SO₃H group is useful as an electrolytematerial for e.g. brine electrolysis or a fuel cell. For example, such apolymer having a —SO₃H group can be used as an electrolyte for anion-exchange membrane or in a catalyst layer for a polymer electrolytefuel cell. Other than such an application, such a polymer having a —SO₃Hgroup can be used for a material of various electrochemical processes asa solid electrolyte material. Further, the —SO₂F group-containingpolymer itself is useful for an application as an optical material, etc.

The entire disclosure of Japanese Patent Application No. 2007-208024filed on Aug. 9, 2007 including specification, claims and summary isincorporated herein by reference in its entirety.

1. A compound represented by the following formula (3):

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.
 2. The compound according to claim 1, wherein eachof —R^(f1)—SO₂F and R^(f2)—SO₂F is a perfluorinated 2-fluorosulfonylethoxy group-substituted alkylene group (the alkylene group has 1 to 3carbon atoms).
 3. A process for producing a compound represented by thefollowing formula (3), which comprises heat-decomposing a compoundrepresented by the following formula (2);

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.
 4. The process according to claim 3, wherein eachof —R^(f1)—SO₂F and —R^(f2)—SO₂F is a perfluorinated 2-fluorosulfonylethoxy group-substituted alkylene group (the alkylene group has 1 to 3carbon atoms).
 5. The process according to claim 3, wherein the compoundrepresented by the above formula (2) is produced from a compoundrepresented by the following formula (1) through (a) a step ofepoxidation, (b) a step of forming a dioxolane ring and (c) a step offluorination;

wherein each of R¹ and R² which are independent of each other, is a C₁₋₈alkylene group which may have an etheric oxygen atom between carbonatoms and of which some or all of hydrogen atoms may be substituted byfluorine atoms.
 6. The process according to claim 5, wherein each of—R¹—SO₂F and —R²—SO₂F is a 2-fluorosulfonyl-tetrafluoroethoxygroup-substituted alkylene group (the alkylene group has 1 to 3 carbonatoms).
 7. A compound represented by the following formula (2):

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.
 8. The compound according to claim 7, wherein eachof —R^(f1)—SO₂F and R^(f2)—SO₂F is a perfluorinated 2-fluorosulfonylethoxy group-substituted alkylene group (the alkylene group has 1 to 3carbon atoms).
 9. A process for producing a fluorosulfonylgroup-containing polymer, which comprises polymerizing at least onecompound represented by the following formula (3), or at least one sucha compound and at least one polymerizable monomer copolymerizable withsuch a compound:

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.
 10. A fluorosulfonyl group-containing polymercomprising at least one type of monomer units represented by thefollowing formula (3U), or at least one type of such monomer units andat least one type of other monomer units:

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.
 11. The fluorosulfonyl group-containing polymeraccording to claim 10, which has a molecular weight of from 5×10³ to5×10⁶, and which, when containing said other monomer units, containsfrom 0.1 to 99.9 mol % of monomer units represented by the formula (3U).12. A process for producing a polymer containing sulfonate groups orsulfonic acid groups, which comprises subjecting the fluorosulfonylgroup in the fluorosulfonyl group-containing polymer according to claim10 to an alkali hydrolysis, or to such an alkali hydrolysis, followed byan acid treatment.
 13. A sulfonic acid group-containing polymercontaining at least one type of units represented by the followingformula (5U), or at least one type of such units and at least one typeof other units;

wherein each of R^(f1) and R^(f2) which are independent of each other,is a C₁₋₈ perfluoroalkylene group which may have an etheric oxygen atombetween carbon atoms.
 14. The sulfonic acid group-containing polymeraccording to claim 13, which has a molecular weight of from 5×10³ to5×10⁶, and which, when containing other units, contains from 0.1 to 99.9mol % of units represented by the formula (5U).
 15. An electrolytematerial for polymer electrolyte fuel cells, which comprises thesulfonic acid group-containing polymer according to claim 13.